Radio Stays on and Park Assist Malfunction?

My vehicle listed above started having strange electrical issues a few weeks ago. I had a spill into the large tray in the center console, but I don't think anything leaked into the area underneath. But about the same time, the battery ran down completely, and it turned out the radio had stayed on for about a week while I was out of town. The volume controls on the steering wheel no longer work and the radio produces no sound from any speakers. Also, the park assist function for the rear back up sensors stopped working. I've been told this could be a BCM malfunction or a RAP switch failure. The interior lights and headlights do go off about 30 seconds after the ignition is turned off as normal. Where would you suggest I start looking? Thanks.